The present invention relates generally to an apparatus for sterilizing objects and, more particularly, is directed to a novel actuating mechanism for a sterilization apparatus.
It is well known to sterilize surgical, medical, dental and other instruments and the like by exposing them to a gaseous sterilant in a closed container. In order to provide an arrangement that can be readily used for the sterilization of instruments, it is further known to provide the gaseous sterilant in an ampule, as disclosed, for example, in U.S. Pat. No. 3,476,506, having a common assignee herewith, the entire disclosure of which is incorporated herein by reference.
As disclosed therein, the ampule is in the form of a sealed gas-tight container made from a breakable material, such as glass, which is impervious to the sterilant. In order to provide for easy braking of the ampule, the ampule is preferably provided with a spout connected to the main body thereof by a reduced diameter neck, with the reduced diameter neck being provided with a score line for easy braking. The sterilant is preferably ethylene oxide, although any other suitable sterilant can be used. The ethylene oxide is maintained largely in a liquid state when sealed in the ampule.
The ampule is inserted and hermetically sealed in an inner plastic gas release bag or pouch made from a semi-permeable material such as polyethylene. In order to sterilize the instruments, the neck of the ampule is manually broken along the score line, while the ampule is in the gas release bag. As a result, the ethylene oxide boils so that all of the liquid is converted into gaseous form and released into the gas release bag to fill the same.
Thereafter, the gas release bag is inserted and sealed in an outer plastic liner bag, along with the instruments to be sterilized. Because the gas release bag is made from a semi-permeable material, the vapor of the sterilant will diffuse through the semi-permeable walls of the gas release bag at a rate which provides a sufficient concentration of sterilant within the liner bag to sterilize the instruments. The rate of diffusion of the sterilant through the walls of the gas release bag may be controlled by selecting the proper dimensions, thickness and pore size (i.e. permeability) of the gas release bag.
The liner bag is also made of a semi-permeable material, but provides a rate of diffusion to the atmosphere which does not permit a toxic level of the gaseous sterilant to reach the atmosphere surrounding the liner bag.
See also U.S. Pat. Nos. 3,505,775; 4,937,046; and 5,082,636, all having a common assignee herewith, and the entire disclosures of which are incorporated herein by reference.
With this arrangement, however, breaking of the ampule while it is in the gas release bag can become cumbersome, and during some times, difficult. This is because it is necessary to hold both the main body of the ampule and the spout separately, in order to break the neck along the score line, while the ampule is in the gas release bag.
Further, with such an arrangement, the permeability of the gas release bag is selected so that the peak concentration of the ethylene oxide in the liner bag occurs between two and three hours after the ampule has been broken. Because of this long time period, the user is able to break the ampule in the gas release bag, and then place the gas release bag within the liner bag, without being exposed to the gas.
However, if the gas release bag or pouch is fabricated of a highly porous, paper-like plastic material, such as that commonly sold under the trademark "TYVEK", the peak concentration of the gas is reached within the first ten minutes of release, yielding a higher initial ethylene oxide concentration and more rapid aeration from the same dose, where the dose is equal to the concentration multiplied by time. In such case, to provide protection for the user, the ampule must be broken while it is sealed in the gas release bag and while the gas release bag is sealed in the liner bag. As a result, it is more difficult to manipulate the ampule to break the same while the ampule is located in the sealed liner bag filled with objects to be sterilized, than in the case where the ampule is only in the gas release bag.
Further, with such an arrangement, no ethylene oxide is released by the gas release bag for about 15 minutes after the ampule is broken, and the peak concentration of ethylene oxide is reached in approximately 3 hours. It will be appreciated that this system is designed to operate at room temperature, and that the entire process takes approximately 38 hours, which includes a sterilization cycle that takes approximately 12 hours, followed by a 2 hour purging of the liner bag of ethylene oxide before the operator can open it safely, and followed lastly by a 24 hour cycle to air gas absorbent materials before they can be used. This operation, however, is unduly lengthy from a practical standpoint.
U.S. Pat. No. 4,528,268, also having a common assignee herewith, discloses an apparatus for testing the sufficiency of sterilization. With this apparatus, an ampule is held within a sleeve which, in turn, is held within a test tube. The test tube has a wedge-shaped bottom and the spout of the ampule faces the wedge-shaped bottom. An axially oriented plunger is slidably provided at the opposite open end of the test tube in order to bias the ampule downwardly in the axial direction of the test tube, whereupon the spout engages the wedge-shaped bottom and the ampule breaks along the score line.
However, there is no disclosure of using this apparatus for actually sterilizing objects in the manner taught by the aforementioned U.S. Pat. Nos. 3,476,506 and 5,082,636.